Improvement in reversible center-pinions for watches



F. E. SM1TH.

REVERSIBLE CENTER PINION FOR WATCHES; No. 171,058. Patented Dec. 14,1875.

W'it ness es I nvento 1' QQMW UNITED STA ES PATENT OFFICE. V

FRANK E. SMITH, OF SAN JOSE, CALIFORNIA.

IMPROVEMENT lN REVERSIBLE CENTER-PINIONS FOR WATCHES.

Specification forming part of Letters Patent No. 171,058, dated December 14, 1875 application filed July 7, 1875.

To all whom it may concern:

- Wheels, in order to allow the pinion to turn in a reverse direction, and receive the strain upon the mechanism of the watch in case the mainspriug should break.

My invention is fully illustrated in the accompanying drawings, in which Figure l is a transverse section of my device. Fig. 2 is a side elevation, with a part broken away. Fig. 3 is a side elevation.

01 represents the arbor, which carries the center-wheel for transmitting the power derived by the pinion B from the spring-barrel to the train of gearing comprising the operative mechanism of a watch. The pinion B has an axial bore, which permits it to be slipped on over the arbor 61, so that it will lie close to the center-wheel, and the power which is transmitted to the centenwheel must first pass through the pinion, and this power is always transmitted in one and the same direction. In order to secure this pinion to the arbor d of the center-wheel, so that it will engage with the arbor when turned in one direction, and rotate freely independent of the ar bor when turned in a reverse direction, I make a narrow mortise, c, diametrically through the arbor at the point which the pinion is to permanently occupy. I then construct a springpawl, c, to fit in this mortise inthe following manner: This spring-pawl is made in the form of a U, with its points or ends 2' i sufficiently spread to cause them to project slightly from the mortise on each side of the arbor when it is placed in the mortise, thus providing two catches, one on each side of the arbor, both of which are formed on the opposite ends of the same U-shaped spring. In the bore of the pinion B I then make two or more notches, 0 0. One side of each notch is inclined, while the opposite side is straight, in the manner of forming ratchet-teeth, so that the points or ends 71 '11 of the spring-pawl will engage with them on opposite sides of the arbor. Now, when the pinion B is turned so as to cause the projecting points or ends of the springpawl to engage with the straight sides of the notches, the pinion and arbor will rotate together, and the power will be transmitted through them to the operative mechanism of the watch; but in ca e of the rupture or breakage of the main spring the recoil or reverse movement of the springbarrel will cause the pinion to rotate in a reverse direction, so that the pressure ot the teeth or points it is transferred to the inclined sides of the notches, and the consequent compression of the spring will allow the teeth to pass over the notches without catching, thus permitting the pinion to rotate freely and independent of the arbor until the recoil ceases.

The above-described arrangement is very simple, and can be cheaply applied, while it does not encumber the pinion with outside attachments, which are at the same complicated and unsightly in a watch.

Having thus described my invention, what 

